Starting circuit for fluorescent lamps



June 16, 1942. E. c. DENCH STARTING CIRCUIT FOR FLUORESCENT LAMPS File dMay 4, 1940 aww 1 4. 2 2 6 9 4 w z 2 2 Mm z M :0 l9; r m (1 0 Z M w 7 y37% 44 INVENTOR BY MM ATTORNEY Patented June 16, 1942 2,286,790 srsa'rmccracUrr roa rwoaesoan'r LAMPS Edward Charles Dench, South Orange, N. 1.,assignor to Westinghouse Electric & Manufacturin; Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application May 4, 1940,Serial No. 333,307

6 Claims.

excited by the invisible radiations generated by the discharge so as toconvert the invisible radiations into visible radiations.

These lamps operate from the customary source of domestic potential of115 volts, but have a very poor power factor correction when sooperated. In order to overcome this difiiculty and more closely approachunity power factor, it has been suggested to operate such lamps inseries from the domestic source of supply. This, however, involvesnumerous difliculties in initiating a discharge in such series connecteddischarge lamps.

It is accordingly an object of the present invention to provide acircuit arrangement wherein the series connected discharge lamps may bereadily started with a fidelity of operation throughout the life of thelamps.

Another object of the present invention is the provision of a gaseouselectric device which operates to initiate a discharge in a plurality ofgaseous discharge lamps connected in series, with the gaseous electricdevice consuming no energy from the source of supply during theoperation of the series connected discharge lamps.

Another object of the present invention is the provision of a startingand operating circuit for a plurality of series connected dischargelamps operable at substantially unityv power factor and wherein agaseous electric device is utilized for initiating a discharge in thelamps with the gaseous electric device consuming no energy from thesource of supply during operation of the lamp and which device operateswith fidelity dur ing the entire life thereof.

Still further objects of the present invention will become obvious tothose skilled in the art by reference to the accompanying drawingwherein:

Fig. 1 is a diagrammatic illustration of a starting and operatingcircuit in accordance with the present invention; and

Fig. 2 is a cross-sectional view of a novel gaseous electric deviceconstructed in accordance with the present invention and as shown as anelement of the starting and operating circuit of Fig.

Referring now to the drawing in detail, a plurality of gaseous electricdischarge lamps 5 and 6 are shown which may be of the fluorescent typehaving a coating on the interior surface of the envelope (not shown)which is excited by the invisible radiations generated by the ensuingdischarge between the electrodes. As will be noted the lamp 5-isprovided with oppositely disposed filamentary electrodes 1 and 8, andsimilarly the discharge lamp 6 is provided with electrodes 9 and I0, allof which filamentary electrodes may be provided with an electronemissive coating, such as an oxide of barium, strontium, or the like,adapted to emit electrons when heated. One terminal of the filamentelectrode 1 is connected by means of a conductor 12 and an inductanceelement 13 to one side of the source of supply of the customary domesticpotential of volts L-l. Likewise, one terminal of the filamentaryelectrode it of the lamp 6 is connected by means of a conductor ll tothe opposite side of the source of supply L-2. One terminal of theelectrode 8 of the lamp 5 and the electrode 9 of the lamp 8 areconnected together by a conductor 15 which thus connects the lamps inseries with each other to the source of supply L-i, L-2.

In order to connect the respective filamentary electrodes of the lamps 5and 8 in series with each other, a gaseous electric device it isemployed. This device is similar in some respects to that shown in myPatent No. 2,200,443, issued May 14, 1940, and assigned to the sameassignee as the present invention.

As therein shown, a glow relay device is employed for connecting theelectrodes of a single lamp in a series heating circuit with the sourceof supply. Upon the application of a potential from the source of supplya glow discharge occurs between the electrodes of the device. Since oneof the electrodes is a heat responsive element, heating thereof causesmovement of the heat responsive electrode until it engages the otherelectrode. This engagement of the electrodes short-circuits thedischarge, thus positively connecting the filamentary electrodes of thedischarge lamp in a series heating circuit to the source of supply.

The electrodes of the lamp are thus heated to an electron emittingtemperature; and upon cooling of the heat responsive electrode of thegaseous relay device, the engaged electrodes separate, thus causing ahigh voltage surge to be t'ain substantially unity power factor.

impressed upon the lamp, causing the initiation of a discharge betweenthe heated electrodes. Thus the discharge continues in the lamp untilinterruption of the energy supplied thereto, with the glow dischargedevice consuming no current during operation of the lamp.

While such device operates very effectively and efficiently with asingle lamp, it is not practical to employ such a glow relay device foreach individual discharge lamp when such lamps are connected in serieswith the source so as to ob- For example, a glow relay device such asshown in the above noted patent cannot be employed with each of thelamps and 6 as shown in Fig. 1 because the line voltage is approximately115 volts. If an individual glow relay tube were employed for each lamp,this line voltage would be divided between the glow relay tubes, whichvoltage is insufficient to operate the relays for the purpose ofinitiating a discharge in the series connected discharge lamps 5 and 6.

To overcome this diiiiculty and at the same time provide a startingcircuit for a plurality of series connected discharge lamps, an improvedtype gaseous electric relay device is herein provided which operatessomewhat in the manner of that shown and described in my above notedpatent.

As will be noted in Fig. 2, the modified form of glow relay device [5 isprovided with a plurality of electrodes arranged in groups or pairs andin the embodiment shown, one pair provided for each discharge lamp inthe series. Such electrodes are enclosed within an evacuated containerI! which is provided with an ionizable medium which may comprise aninert gas or mixture thereof, such as argon, neon, helium, etc. A heatresponsive electrode I8, which may comprise a substantially U-shapedbimetallic element, is supported by a leading-in and supportingconductor 19 with the free end of the bimetallic element being disposedadjacent an electrode 20 of small area likewise supported by aleading-in conductor 22.

The bimetallic electrode I8 is provided at its extremity with a contactterminal 23 as well as an electron emissive material in the form of ametal of high electron emissivity, such as zinc or the like, or acoating of electron emissive material similar to that with which thefilamentary electrodes of the discharge lamps 5 and 6 are provided. Inaddition, the device I is provided with anotherheat responsive orbimetallic electrode 24 identical to the previously described electrodei8, and a cooperating electrode 25 identical to that of the previouslydescribed electrode 20. Since a pair of cooperating electrodes such asI8 and 20 are provided for each lamp in the series which are ofidentical construction, further detailed description of such electrodesis believed to be unnecessary.

It will be noted, however, by reference to Fig. 2 that the cooperatingelectrodes of small area 25 and 25 are disposed adjacent each other andinterposed between the heat responsive or bimetallic electrodes l8 and24 of each pair for a purpose to be hereinafter described.

Referring again to Fig. i, it will be noted that in order to connect theelectrodes 1 and 3 of the lamp 5 in series with each other, aspreviously mentioned. a conductor 32 connects one terminal of thefilamentary electrode 1 to the heat responsive electrode IQ of thegaseous electric device I6, and the electrode 20 thereof is connected bya conductor 3.3 tothe remaining terminal of the filamentary electrode 8.Likewise, a conductor 34 connects the remaining terminal of thefilamentary electrode ID of the lamp 6 to the heat responsive orbimetallic electrode 24 of the device l6, and similarly conductor 35connects the electrode of smaller area 25 to the remaining terminal ofthe filamentary electrode 9 of the lamp 6.

The startingand operating circuit above described operates in thefollowing manner. Upon closure of a suitable switch (not shown), theline voltage of approximately 115 volts is applied to the electrodes l8and 24 of the gaseous elec-' tric device l6 from one side of the sourceof supply L-l through the inductance l3, conductor l2, filamentaryelectrode 1 and conductor 32, and from the opposite side of the sourceof supply L2 through the conductor l4, filamentary electrode in andconductor 34.

.These two electrodes l8 and 24, being provided with an electronemissive material, cause a glow discharge to occur therebetween sincethe -full line voltage of H5 volts is suflicient to ionize the mediumwithin the envelope I1. The resulting discharge heats the electrodes I8and 24 and, since they are heat responsive of bimetallic, they will flexinto engagement with their respective cooperating electrodes 20 and 25.

Since the source of supply L-i, L-2 is alternating current, actually oneor the other of the electrodes i8, 24 operate slightly ahead of theother, depending upon which has functioned the greater percentage of thetime during the momentary discharge as cathode. Regardless 01' whichparticular electrode engages its cooperating electrode of smaller area,the operation is the same.

Assuming, therefore, that the heat responsive electrode I8 is heatedmore rapidly, the contact terminal 23 carried by the extremity thereofwill engage its cooperating electrode 23, thereby short-circuiting thesetwo electrodes and connecting the filamentary electrodes I 'and 5 of thelamp 5 in series. The completion of this series heating circuit for thelamp 5 thus applies the voltage from the source directly between theremaining electrodes, namely, 24 and 25, again causing a glow dischargebetween these two electrodes with further heating of the heat responsiveelectrode 24 until it moves into engagement with the electrode 25,short-circuiting the. same and extinguishing the discharge.

Engagement of these two electrodes 24 and 25 thus connects thefilamentary electrodes {and ID of the lamp 6 in series with each otherand by the same token, since the electrodes 1 and 3 of the lamp 5 are inseries with each other, they are connected in series with the electrodes9 and III of the lamp 6 so that a series heating circuit for all of thefilamentary electrodes of all the series connected lamps is thus formed.All of the filamentary electrodes of the series connected dischargelamps are thus heated to an Such discharge will continue so long as theswitch (not shown) in the source of supply remains closed and, duringthe continuance of such discharge, no energy is consumed by he gaseouselectric device l6 since the resistance thereof is now higher than thatof the series connected lamps and 6 and the total voltage drop of thelamps 5 and 6 is approximately 80 volts, which renders the voltageavailable insufiicient ior'further operation of the gaseous relay devicel6, so that no glow discharge occurs between the cooperating electrodesof eachgroup in the device l6 and it remains dormant.

If, however, for any reason a discharge fails to occur between theheated filamentary electrodes of the respective lamps 5 and 6 upondisengagement of the electrodes of the gaseous electric device IS, thelatter repeats its cycle of operation, causing initiation of thedischarge in the lamps 5 and 6. However, due to the construction of thegaseous electric device "3, it is very positive in its operation andvery rarely fails to initiate the discharge during its initial cycle ofoperation; but in any event, its cycle of operation continues with suchrapidity that a discharge is initiated in the series connected dischargelamps within approximately a second or so.

It thus becomes obvious to those skilled in the art that a starting andoperating circuit for a plurality of gaseous discharge lamps is hereinprovided so that the lamps operate at substantially unity power factorinasmuch as the lamps are connected in a series circuit with the sourceof supply. Moreover, by the provision of a novel gaseous relay device,which operates to connect the electrodes of the gaseous discharge lampsin a series heating circuit with each other and with those of theremaining lamps of the series with such device subsequently operating tointerrupt the series heating circuit and cause a high voltage surge tobe impressed across the electrodes of the lamp, initiation of adischarge is facilitated.

In addition, such device is provided with a pair of electrodes for eachlamp in the series and consequently operates with fidelity to performits starting sequence for 'the series connected discharge lamps and,once the discharge is initiated, such device consumes no energy from thesource of supply, thus increasing the efficiency of operation of therespective series connected discharge lamps.

Although one specific embodiment of the present invention has been shownand described, it is to be understood that other modifications thereofmay be made without departing from the spirit and scope of the appendedclaims.

I claim:

1. An electric circuit for starting and operating at substantially unitypower factor a plurality of gaseous electric discharge lamps providedwith electrodes adapted to be heated to an electron emitting temperaturefrom a source of electrical energy and having an ionizable mediumtherein comprising a source of electrical energy for energizing saidlamps, an induc tance element interposed between said source and one ofthe electrodes of one of said lamps, and means for connecting theelectrodes of all of said lamps in series to cause heating of saidelectrodes to an electron emitting temperature comprising an auxiliarydischarge device provided with a pair of electrodes therein for eachdischarge lamp in the series and between which engagement thereof andextinguishment of said momentary discharge to complete a series heatingcircuit for the electrodes of said lamp, and said pairs of electrodesbeing operable to thereafter interrupt said heating circuit and cause anattendant voltage surge .from said inductance element for initiating adischarge in all of said series connected discharge lamps.

2. An electric circuit for starting and operating at substantially unitypower factor a plurality of gaseous electric discharge lamps providedwith electrodes adaptedto be heated to an electron emitting temperaturefrom a source of electrical energy and having an ionizable mediumtherein comprising a source of electrical energy for energizing saidlamps, an inductance element interposed between said source and one ofthe electrodes of one of said lamps, and means for connecting theelectrodes of said lamps in series to cause heating thereof to anelectron emitting temperature comprising an auxiliary discharge deviceprovided with a plurality of electrodes therein and between which adischarge occurs upon the application of a potential from said source,one pair of said electrodes including a heat responsive elementinitially heated by a discharge between it and an electrode of anotherpair and operable to engage the electrode of its pair to short-circuitthe same and to connect the electrodes of one lamp in a series heatingcircuit and operable to cause a momentary discharge between the otherpair of electrodes, said other pair of electrodes including a heatresponsive element heated by the momentary discharge and operable toengage the electrode of its pair to short circuit the same andextinguish said discharge and to connect the electrodes of the otherlamp in a series heating circuit, and said device being operable tothereafter interrupt said heating circuit for the electrodes of saidlamps and cause an attendant voltage surge from said inductance elementfor initiating a discharge in all of said series connected dischargelamps.

3. An electric circuit for starting and operating at substantially unitypower factor a plurality of gaseous electric discharge lamps providedwith electrodes adapted to be heated to an electron emitting temperaturefrom a source of electrical energyand having an ionizable me diumtherein comprising a source of electrica energy for energizing saidlamps, an inductance element interposed between said source and one ofthe electrodes of one 01' said lamps, and means for connecting theelectrodes of said lamps in series comprising an auxiliary dischargedevice having a pair of electrodes for each lamp included in the seriesbetween which a discharge occurs upon the application of a potentialthereto, each pair of said electrodes including a heat responsiveelement adapted to emit electrons to initially cause a glow dischargebetween one 01 the electrodes of each pair thereby heating each heatresponsive electrode with attendant movement of one of said heatresponsive electrodes into contact with the other electrode of its pairto extinguish said discharge and to connect the electrodes of theirassociated lamp in 'a series heating circuit with the electrodes of theremaining lamps of the series and to cause a momentary discharge betweenthe remaining heat responsive electrode and the other electrode of itspair to short circuit the same and extinguish said momentary discharge,and said device being thereafter operable to interrupt said heatingcircuit for the electrodes of said lamps and cause an attendant voltagesurge from said inductance element for initiating a discharge in all ofsaid series connected discharge lamps.

4. A gaseous electric device comprising an envelope provided with anionizable medium therein, a plurality of electrodes within said envelopearranged in co-operating groups, one electrode of each group being aheat responsive electrode adapted to emit electrons to cause a dischargebetween one of the electrodes of each group thereby heating each heatresponsive electrode with attendant movement oi one of said heatarranged in pairs, one electrode of each pair being a heat responsiveelectrode adapted to emit electrons to initially cause a glow dischargebetween one of the electrodes of each-pair thereby heating each heatresponsive electrode with attendant movement of said heat responsiveelectrodes-into contact with the other associated electrode 01 its'pairto short-circuit the same and extinguish the discharge and to thereaftercause a momentary discharge between the remaining heat responsiveelectrode and the associated electrode of its pair to short-circuit thesame and extinguish said momentary discharge.

6. A gaseous electric device comprising an envelope provided wtih anionizable medium therein, a plurality of electrodes within said envelopearranged in pairs, one electrode of each pair being a heat responsiveelectrode adapted to emit electrons to initially cause a glow dischargebetween one of the electrodes of each pair thereby heating each heatresponsive electrode with attendant movement of one or said heatresponsive electrodes into contact with the other associated electrodeof its pair to short-circuit the same and extinguish the discharge andto there- 'after cause a momentary discharge between the remaining heatresponsive electrode and the associated electrode of its pair toshort-circuit the same and extinguish said momentary discharge, theother electrodes of each pair being disposed adjacent each other andinterposed between the heat responsive electrode of each pair.

' EDWARD CHARLES DENCH.

